It is the purpose of this project to elucidate the mechanism of the immunologic rejection of tumor grafts and to determine the mechanism of tumor suppression following immunostimulation with BCG. Current areas of investigation are: Determination of optimal conditions for immunization against transplantable syngeneic murine tumors, evaluation of the specificity of immunization evoked by living BCG and fibrosarcoma cells and development of methods for elimination of microscopic metastases remaining after surgery.